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Phytoplankton in the Antarctic deplete silicic acid (Si(OH)4) to a far greater extent than they do nitrate (NO3 -). This pattern can be reversed by the addition of iron which dramatically lowers diatom Si(OH)4:NO3 - uptake ratios. Higher iron supply during glacial times would thus drive the Antarctic towards NO3 - depletion with excess Si(OH)4 remaining in surface waters. New δ30Si and δ15N records from Antarctic sediments confirm diminished Si(OH)4 use and enhanced NO3 - depletion during the last three glaciations. The present low-Si(OH)4 water is transported northward to at least the subtropics. We postulate that the glacial high-Si(OH)4 water similarly may have been transported to the subtropics and beyond. This input of Si(OH)4 may have caused diatoms to displace coccolithophores at low latitudes, weakening the carbonate pump and increasing the depth of organic matter remineralization. These effects may have lowered glacial atmospheric pCO2 by as much as 60 ppm., Cited By (since 1996):108, CODEN: GPRLA, Oceanography, Antarctica

In situ incubation chamber measurements of benthic nutrient recycling rates were made on the Monterey Bay shelf at 100 m during various years and seasons. Variability in nutrient (Si, PO42+, NH3, NO3−) and trace metal (Mn, Fe (II), Cu) fluxes correlate with variability in the amount of organic carbon oxidized on the sea floor. Patterns of primary productivity show a mid-year maxima, consistent with the timing of increased rates of benthic Corg and opal recycling. High rates of Corg rain to the shelf promote nitrate consumption at a rate that equals or exceeds ammonia efflux. Low rates of Corg rain promote greater efflux of DIN; thus these margin sediments provide a negative feedback to local productivity cycles. The efflux of iron (II) from shelf sediments is sufficient to support >100% of new production, yet Fe flux is positively correlated with Corg recycling which lags the maximum in new production. On account of this time lag, diagenetically recycled Fe is not likely a micro-nutrient trigger of new production, but could serve as a positive feedback. Bio-irrigation rates are seasonally variable by 30% but maximal during the maximum productivity months.

The prey items of 108 species representing all 10 families of the suborder Dendronotacea are presented in shortened form from the much larger electronic database accessible on the Web., Cited By (since 1996):9, Invertebrates

We studied the seasonal abundance and spatial distribution of marine mammals in nearshore waters (<1 km from shore) of Monterey Bay, California, during 1999 and 2000. The most abundant mammal was California sea lion, Zalophus californianus, followed by harbor porpoise, Phocoena phocoena, sea otter, Enhydra lutris, and harbor seal, Phoca vitulina. Seasonal abundance of harbor porpoise in the survey area was greatest during winter, pinnipeds were most abundant during autumn, and sea otters were most abundant during spring and autumn. California sea lions were more abundant in 2000 than in 1999. Harbor porpoise were found in water of lesser clarity than expected by chance, and sea lions were found more often in water of intermediate clarity. Distribution of sea otters and harbor seals were not affected by water clarity., Cited By (since 1996):2, Marine Mammals, Birds & Turtles

Leatherback turtles (Dermochelys coriacea) are regularly seen off the U.S. West Coast, where they forage on jellyfish (Scyphomedusae) during summer and fall. Aerial line transect surveys were conducted in neritic waters (<92 m depth) off central and northern California during 1990-2003, providing the first foraging population estimates for Pacific leatherback turtles. Males and females of about 1.1 to 2.1 m length were observed. Estimated abundance was linked to the Northern Oscillation Index and ranged from 12 (coefficient of variation [CV]=0.75) in 1995 to 379 (CV=0.23) in 1990, averaging 178 (CV=0.15). Greatest densities were found off central California, where oceanographic retention areas or upwelling shadows created favorable habitat for leatherback turtle prey. Results from independent telemetry studies have linked leatherback turtles off the U.S. West Coast to one of the two largest remaining Pacific breeding populations, at Jamursba Medi, Indonesia. Nearshore waters off California thus represent an important foraging region for the critically endangered Pacific leatherback turtle.

Leatherback turtles (Dermochelys coriacea) are regularly seen off the U.S. West Coast, where they forage on jellyfish (Scyphomedusae) during summer and fall. Aerial line-transect surveys were conducted in neritic waters (<92 m depth) off central and northern California during 1990-2003, providing the first foraging population estimates for Pacific leatherback turtles. Males and females of about 1.1 to 2.1 m length were observed. Estimated abundance was linked to the Northern Oscillation Index and ranged from 12 (coefficient of variation [CV] = 0.75) in 1995 to 379 (CV = 0.23) in 1990, averaging 178 (CV = 0.15). Greatest densities were found off central California, where oceanographic retention areas or upwelling shadows created favorable habitat for leatherback turtle prey. Results from independent telemetry studies have linked leatherback turtles off the U.S. West Coast to one of the two largest remaining Pacific breeding populations, at Jamursba Medi, Indonesia. Nearshore waters off California thus represent an important foraging region for the critically endangered Pacific leatherback turtle., Cited By (since 1996):16, CODEN: FSYBA, Marine Mammals, Birds & Turtles

Blue whales Balaenoptera musculus were most abundant in April and May while minke B. acutorostrata whales were equally abundant throughout the year. Fin B. physalus and Bryde's whales B. edeni were found but fin whales were more abundant in winter and spring; numbers were negatively correlated with water temperature. Bryde's whales were more abundant in summer and fall; numbers were positively correlated with water temperature. The percentage of identified individual adults that were females with calves was 10.6 for Bryde's and 2.7 for fin whales., Cited By (since 1996):13, Marine Mammals, Birds & Turtles

The authors review how access to historical aerial photograph collections has evolved in response to technological developments and addresses areas for further advancement, with a particular emphasis on developing, preserving, and sustaining online collections. The authors focus specifically on the areas of metadata, the Semantic Web and linked data, and sustainability through collaboration. The article includes brief case studies, highlighting various projects involving the aerial photography collections at the University of Minnesota. The conclusion asserts the critical role played by geographic information librarians in effectively carrying out the strategies described in the article as they relate to the long-term sustainability of digital geospatial collections.

The possible modification of mercury toxicity by selenium in embryos of the Pacific oyster Crassostrea gigas and the larvae of the crab Cancer magister was investigated. Mercury concentration eliciting abnormal development in 50% of the oyster embryos (EC50) was 5.7 μg l-1 (48 h) and mortality in 50% of the crab larvae (LC50) occurred with 6.6 μg l-1 (96 h). The 48 h EC50 for selenium was greater than 10,000 μg l-1 for oyster embryos and the 96 h LC50 for crab zoeae was 1040 μg l-1. The response from each species, when exposed to both toxicants, revealed that a high level of selenium (≥5,000 μg l-1) increased mercury toxicity. Moderate selenium concentrations (10 to 1,000 μg l-1) tended to decrease mercury toxicity, although no statistical verification could be made. The order of administration of toxicants had no effect on the response of Crassostrea gigas embryos. Early developmental stages (≤8 h) of C. gigas embryos were most sensitive to dissolved Hg; toxicant administration 24 h after fertilization resulted in no apparent abnormalities in development., Cited By (since 1996):7, CODEN: MBIOA, Invertebrates

The rate of energy expenditure and acquisition are fundamental components of an animals' life history. Within mammals the otariids (sea lions and fur seals) exhibits energetically expensive life styles, which can be challenging in equatorial regions where resources are particularly limited and unpredictable. To better understand how this energetically expensive life history pattern functions in an energetically challenging equatorial system, we concurrently measured the field metabolic rate (FMR) and foraging behavior of lactating Galapagos sea lions (GSL) rearing pups and yearlings. Females with pups tended to forage to the north, diving deeper, epi and mesopelagically compared to females with yearlings, which foraged to the west and performed dives to the sea bed that were shallower. FMR did not differ between females with pups or yearlings but, increased significantly with % time spent at-sea. Females with yearlings had higher water influx, suggesting greater food intake, but had lower body condition. The FMR (4.08 +/- 0.6 W/kg) of GSL is the lowest measured for any otariid, but is consistent with Galapagos fur seals which also exhibit low FMR. The observation that these two otariids have reduced energy requirements is consistent with an adaptation to the reduced prey availability of the Galapagos marine environment compared to other more productive marine systems., In Press